1. Field
The present invention relates to an electronic device, and more particularly to an electronic device which contains a heat generator such as a semiconductor, and a cooling unit for cooling the heat generator.
2. Description of the Related Art
Accompanied with the recent trend of speeding up of the information processing performed by an electronic device or a personal computer, the heat value of the semiconductor element such as CPU has been increasing. Accordingly, forced cooling of the semiconductor element has become indispensable for maintaining its performance.
Besides the CPU, the heat value of the semiconductor element for the high-speed signal processing, for example, a graphic controller used for image processing has been increasing. Recently, the number of the electronic device of type which contains a plurality of semiconductor elements requiring forced cooling in a single enclosure has been increasing.
The forced cooling of the CPU or the like has been performed in various ways. For example, the forced air cooling is performed by transmitting heat of a heat receiver thermally connected to the heat generator (CPU) to a radiator through a heat pipe so as to perform the forced cooling of the radiator using a fan and the like.
JP-A 2003-97892 discloses the electronic device as one of the aforementioned types of the technology. The disclosed electronic device is a notebook PC having its main body connected to a panel portion via hinges such that they are opened and closed. The main body contains components in a thin enclosure, for example, the heat generator such as the CPU and a cooling unit. Vent holes are formed in a side wall of the enclosure, and the cooling unit is disposed adjacent to the vent holes. Cooling air of the cooling unit is discharged outside the enclosure through those vent holes.
The cooling unit includes a radiator, a cooling fan, a heat pipe, and a heat receiver. The heat receiver at one end of the heat pipe is thermally connected to the heat generator (CPU). The other end of the heat pipe is thermally connected to the radiator such that the heat of the heat generator (CPU) is transmitted to the heat pipe via the heat receiver, and further transmitted to the radiator.
Heat exchange is performed between a plurality of fins of the radiator and cooling air generated by the cooling fan. The heated cooling air is discharged outside through the vent holes.
In the electronic device of the disclosed type, all the heated cooling air cannot be discharged outside the enclosure. The heated cooling air partially flows back into the enclosure.
The heated cooling air may be efficiently discharged by arranging the cooling fin and the radiator as adjacent to the vent holes (side wall) as possible. However, it is difficult to completely eliminate the gap between the side wall and the radiator in view of operability of assembling the cooling fin and the radiator with the enclosure or limitation in arrangement of the fixation member.
Part of the heated cooling air impinges against the wall of the vent hole, and passes through the gap to return into the enclosure as the flow back of the cooling air.
As a result, the temperature inside the enclosure increases to raise the temperature of the cooling air generated by the cooling fan. This may deteriorate the performance for cooling the heat generator. Accordingly, the cooling fan or radiator are required to be enlarged conforming to a predetermined requirement for the cooling performance.
The temperature rise in the enclosure may adversely affect other semiconductor elements and electronic parts which require no forced cooling.